I am putting an 2004 LS1with T56 6 speed manual transmission in a 68 Firebird. The motor is out of a 2004 GTO. I'm 19 and making about $7/hr so cannot afford a kit so I (legally) scrounged the wiring harness and computer out of a 2000 Corvette. My problem is I don't know how to hook the "simple" 4 wire harness. I already put a Painless wiring harness in the Firebird (before I began the engine swap). Well Painless ain't painless. So if you had any tips on how to adapt the 2000 computer and harness to work with the 2004 LS1 in a 68 Firebird that already has a painless wiring harness installed, I would be real appreciative.

This is my second car. My other one is a 72 Chevelle with a 454. I've built a 350 for my 86 Silverado.  I just haven't done the computer stuff yet and that is where I need some tips. There is a lot on the web but I haven't found anything to help with this.

Jmoney in Rowlett TX

You are right about painless wiring.  While they may make an ok product,  their tech help is worthless.  Your best bet is send in the factory harness as a core allowance and have an aftermarket harness made for the engine.  The other problem you will have is the antitheft in the engine computer.  EFI Wiring can supply you with a harness and antitheft generator for approximately $600.  If you would like to contact them you can Email me for the info.  I have dealt with them in the past and they are excellent with tech help and will not #### you.   booseef@comcast.net